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Effect of Posture and Cardiac Output on Cerebral Autoregulation
Author(s) -
Deegan Brian,
Geraghty Maria C,
Hodgeman Ryan,
Reisner Adam,
Serrador Jorge M
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.2_supplement.76
Subject(s) - autoregulation , cerebral autoregulation , cardiology , cardiac output , medicine , hemodynamics , blood pressure
Cerebral autoregulation, the ability to maintain cerebral blood flow (CBF) is essential to healthy neuronal function. While arterial pressure decreases are known to affect CBF, the role of cardiac output remains unclear. We examined the effect of a suddent pressure drop (thigh cuff release) on both CBF and cardiac output in the supine and seated positions. Cerebral flow velocity (TCD) in the middle and anterior cerebral artreries (MCA & ACA), blood pressure (photoplethysmography), heart rate (ECG), end‐tidal CO 2 were directly measured and cardiac output, stoke volume and total peripheral resistance were estimated using the Modelflow method during 3 thigh cuff releases in both positions. Mean arterial pressure decreased immediately following thigh cuff release and remained depressed while CBF initially decreased then returned to baseline levels within the first 15 seconds. Autoregulatory indexes decreased from supine (MCA: 6.2±0.4; ACA: 5.9±0.4) to upright (MCA: 3.8±0.4; ACA: 4.0±0.4, P<0.01). In contrast cardiac output increased in both positions, while only supine stroke volume increased. These data suggest a possible role for cardiac output, however, the similar response in supine and upright when CBF responses differed questions a primary role. Supported by NASA.